Quick troubleshooting guide for steam Turbines.

                         

  Quick troubleshooting guide for steam Turbines

SL No.	Problem	Root cause	Remedy/Action to be taken
1	High bearing vibrations	High lube oil temperature	Maintain normal lube oil temperature 40-42 deg C or as per OEM recommendations
		More clearance in bearing	Maintain bearing clearance within the limit as recommended by OEM
		Contaminants/burs in oil	1.Ensure oil centrifuge is in service and is running in clarification mode 2.Get tested the oil parameters yearly and ensure all parameters are within limit
		Over load operation	Operate the Turbine at or within its maximum capacity
		Malfunction of the vibration sensor	Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.
2	High bearing temperature (Journal)	High lube oil temperature	Maintain normal lube oil temperature 40-42 deg C or as per OEM recommendations
		Low lube oil pressure	Maintain correct lube oil pressure at all bearing inlet
		Over load operation	Operate the Turbine at or within its maximum capacity
		Less clearance in bearing	Maintain bearing clearance within the limit as recommended by OEM
		Malfunction of the temperature sensor	Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.
3	High bearing temperature (Thrust)	High lube oil temperature	Maintain normal lube oil temperature 40-42 deg C or as per OEM recommendations
		Low lube oil pressure	Maintain correct lube oil pressure at all bearing inlet
		Operation of the Turbine at more exhaust flow (Active side thrust side bearing temperature will increase)	Operate the turbine well within the designed/OEM recommended steam flow
		Operation of the Turbine at more extraction or bleed steam flow (Non-active side thrust bearing temperature will increase)	Operate the turbine well within the designed/OEM recommended steam flow
		Improperly set Rotor during overhauling	Rotor centring should be corrected during overhauling
		Malfunction of the temperature sensor	Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.
4	High axial displacement	Operation of the Turbine at more extraction or bleed steam flow or exhaust flow	Operate the turbine well within the designed/OEM recommended steam flow
5	Turbine Over speed/High speed	Sudden load throw/off	Tuning governing system/actuator to avoid over speeding of rotor during sudden load through off or trips
		Improperly set control valves	Proper setting of control/throttle valves
		ESV & HP-valves Passing (Turbine rotor can go over speed if ESV does not close properly after tripping of Turbine)	Servicing of throttle (HP) valves & ESV during Turbine overhauling
		Malfunction of Governor and control system	Re-tuning of Governor system
		Stuck up of control/throttle valves	Checking Burs & foreign materials in control valves seating ensure no accumulation of dust over there.
6	Turbine running at Low vacuum/exhaust pressure	Condenser cooling (MCWP) water flow/pressure low	Increase MCWP flow and pressure
		Low pressure of ejector motive steam	Increase ejector steam pressure & maintain ejector steam pressure as per OEM recommended
		More Cooling water temperature	1.Increase cooling water flow 2.Increase CT fans speed 3.Operate one more CT fan of required
		Gland sealing steam pressure less	Increase gland steam pressure & maintain as per OEM recommended. Note: Worn out labyrinths’ seals may call for more gland steam pressure than normal recommended
		Operation of the Turbine at more condensing load (Exhaust steam flow to condenser is more)	Reduce the exhaust steam flow & operate the Turbine at optimum exhaust steam flow to condenser
		Worn out ejector nozzles	Replacement of ejector nozzles during shutdowns
		Atmosphere air ingress in condensate system	Check & Arrest air ingress (Check all valves gland, flanges, pipe line flanges, safety/relief valves, CEP strainer flanges)
		Ejector condenser tubes leakage	Check & replace or plug the leaked tubes
		Ejector vacuum steam traps not working properly	Check the traps & adjust steam flow properly. If required service the steam traps
7	Sudden drop of vacuum	MCWP trip/Cooling water flow reduced	Start stand by pump or increase the flow
		Sudden increase in condenser load/ More exhaust steam flow to condenser	Reduce turbine load Increase cooling water flow Then normalise the Turbine load
		Ejector steam pressure reduced	Increase & maintain ejector steam pressure
		Gland sealing steam pressure reduced	Check gland sealing steam control valve & normalise the steam pressure
		Air ingress in condensate system	Check possible ingress points & arrest the leakages.   Potential points for Air ingress are; 1-Air ingress from CEP suction strainer 2-Vacuum breaker valves 3-Ejector safety/relief valves 4-Glands & flanges of valves
		All the CT fans tripped or stopped	Check & start the fans
		Vacuum breaker valve open/malfunction/passing	Check the valve and close properly
8	Hot well level rising	Sudden drop of vacuum	Check the root cause of vacuum drop ( MCWP pump trip or less cooling water flow, ejector steam pressure low etc) and correct it.
		CEP pump tripped	Ensure stand by pump is in AUTO mode & has started immediately
		Air lock in running CEP	Check the reason for air ingress Prime the pump & restart
		Hot well level control valve stuck or malfunction	Check & rectify the valve issue
		CEP to D/A control valve stuck or malfunction	Check & rectify the valve issue
9	Low hot well level	Sudden increase in extraction steam flow	Reduce extraction steam flow
		Hot well level control valve closed/stuck/malfunction	Check and open the hot well level control valve
		CEP to Deaerator control valve stuck/mal function	Check and rectify the issue
		Sudden start of stand by pump	Check and stop the pump if not required
10	Low lube oil pressure	Running oil pump tripped	Ensure stand by pump is in AUTO mode & has started immediately
		PRV stuck or malfunction	Check & rectify the valve issue
		Oil leakage	Check & arrest oil leakage
		Air lock in running pump	Start tart the stand by pump if not started in AUTO and then prime the pump.
		High lube oil temperature	Maintain lube oil temperature within normal limit (40-45 deg C)
		Lube oil filter clogged	Change over the oil filter Clean the filter
11	Low Control oil pressure	Running oil pump tripped	Ensure stand by pump is in AUTO mode & has started immediately
		PRV stuck or malfunction	Check & rectify the valve issue
		Oil leakage	Check & arrest oil leakage
		Air lock in running pump	Start tart the stand by pump if not started in AUTO and then prime the pump.
		Control oil filter clogged	Change over the oil filter Clean the filter
12	High lube oil temperature	Lube oil cooler outlet valve throttled	Open the cooling water outlet valve as per requirement
		Less cooling water flow to Oil cooler	Ensure oil cooler inlet cooling water valve is open 100% & outlet valve is throttled as per requirement
		Less cooling water flow or low ACWP pressure	Increase the cooling water flow & pressure
		Poor heat transfer in oil cooler or tubes fouling	Tubes cleaning & back wash
13	Turbine load/speed hunting	Variation in extraction steam pressure	Maintain extraction steam pressure & flow constant-Talk with end user or process steam.
		Burs on actuator spindles	Clean the actuator shaft & Ensure oil purification unit is in service
		Control oil pressure fluctuation	Ensure accumulator is healthy and its operating pressure is at least 85-90% of control oil operating pressure.
		Contamination in oil	Ensure oil purification unit is in service.
		Improper tuning of governor	Tune the Governor properly
		Tightness in actuator links/resistance in the movement of linkages	Clean & lubricate the actuator linkages & ensure free movement
14	More specific steam consumption of Turbine	Pressure & Temperature of main steam are low	Maintain the correct pressure & temperature
		Low vacuum	Maintain the vacuum on higher side
		High exhaust temperature	Maintain the exhaust temperature in the range of 40-50 deg C or as per exhaust pressure
		Operation of the Turbine at lower/partial loads	Operate the Turbine at higher loads or at full capacity
		More clearance in labyrinth seals	Maintain OEM recommended clearance between rotor & casing during Turbine major overhauling
		More extraction steam flow than recommended	Reduce the extraction flow & maintain as per HMBD
		More bleed steam flow than recommended	Reduce the bleed steam flow & maintain as per HMBD
15	High wheel chamber pressure	Scaling of rotor blades	1-Maintain water and steam quality as per design 2-Descaling of rotor blades during Turbine overhauling
		Less clearance in labyrinth seals	Maintain OEM recommended clearance between rotor & casing during Turbine major overhauling

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Travelling grate Boiler cold start up procedure

 

1.Objective:

This document is created to provide enough information to operation team for or carrying out the Boiler cold start up activity safely and smoothly.

2.Equipment details:

Make: XXX

Working pressure/Temperature: 110 kg/cm2/545 deg C

Capacity: 115 TPH

 3.Responsibility:

Shift In charge, Control room engineers and Boiler operators

 4.Recommended Safety PPEs:

Safety shoes, safety helmet, Face shield, Safety goggles, Boiler apron, hand gloves, ear plugs

 5.Tools/resources required:

 Fire wood, charcoal, diesel and pocking rods, walkie- talkies, Bagasse, coal, tractor dozers, JCB etc

 6.Man power required:

Shift In charge, Boiler Control room engineer, Boiler 1^st class and 2^nd class operator, Ash handling operator, Bunker/Silo operator, Fuel yard operators, Mechanical technicians unskilled labours for Boiler and supporting E&I engineer/Technician.

 

7.Potential Hazards Identified:

Back fire, flue gas leakage, steam & hot water leakages, employees over confidence, poor housekeeping, miss communication, slip/trip, entanglement, explosion/burst etc

 

8.Safety Checks and precautions:

• Ø  Ensure all the required competent man power is available and are using job related specific PPEs.
• Ø  Ensure all the resources are available.
• Ø  Ensure adequate illumination at all the operating/working areas.
• Ø  Ensure proper ventilation at all the operating/working areas
• Ø  Ensure no any slippery area or accumulation of water at all the operating/working areas
• Ø  Ensure no walkway/road blocks
• Ø  Ensure proper housekeeping at all the operating/working areas
• Ø  Ensure firefighting system/appliances is healthy and ready to use on immediate requirement
• Ø  Avoid use of mobile while working
• Ø  Ensure all the rotating parts of equipment are guarded fully
• Ø  Ensure all the hot surfaces of the Boiler are insulated properly
•  
• 9.Pre-start up checks-I
• Ø  Ensure all maintenance activities on Boilers are completed & work permits are closed and equipment are normalised for operation.
• Ø  Ensure all equipments pre-start up trials conducted and are healthy to operate continuously.
• Ø  Ensure Boiler’s all man hole doors (Furnace, super heater, bank zone, drum, economiser, plenum hopper, furnace front hopper etc) are closed.
• Ø  Ensure Boiler thermal expansion pointers are available at all the desired locations and their initial readings are okay.
• Ø  Ensure ESP and APH man hole doors are closed.
• Ø  Ensure all safety valves Gags are removed.
• Ø  Ensure steam drum vent, super heater vents and drains are open
• Ø  Ensure start up vent MOV is open and control valve is closed initially
• Ø  Ensure water wall headers all drains are closed
• Ø  Ensure main steam stop valve and bypass valves are closed
• Ø  Ensure IBD & CBD root valves are open and MOV valve is closed
• Ø  Ensure DM water pump is healthy and its valve to Deaerator is open for initial make up.
• Ø  Ensure HP & LP dosing pumps are healthy and their discharge valves to steam drum and Deaerator are open.
• Ø  Ensure Deaerator inlet steam line valve is closed
• Ø  Ensure deaerator vent line valve and vacuum breaker valves are open
• Ø  Ensure Deaerator outlet to BFP inlet valve is open
• Ø  Ensure all BFPs suction valves are open and discharge valves are closed
• Ø  Ensure all BFPs are healthy to start on immediate requirement
• Ø  Ensure feed control stations (30% and 100%) isolation valves and MOVs are open and control valves are in closed condition.
• Ø  Ensure attemperator isolation valves are open and control valve is in closed condition
• Ø  Ensure Bagasse screw feeders and extractors are heathy and their pre-trial is done
• Ø  Ensure coal spreaders bearing cooling water lines inlet & outlet valves are open
• Ø  Ensure FD & SA air dampers to furnace and OFA ducts are open and are set at desired positions.
• Ø  Ensure instrumentation & service air compressors are healthy and ready for immediate use.
• Ø  Ensure maintenance activities on AHP are completed and ready to take in service
• Ø  Ensure ESP hopper heaters and insulator heaters are ON
• Ø  Ensure APH bypass damper is open and main damper is partially or fully closed
• Ø  Ensure Coal handling plant and Bagasse handling plants are healthy and their interlocks tests are conducted and found okay.

 

10.Pre-start up checks-II

Tank level

• Ø  Ensure Drum level is 40-50%
• Ø  Ensure Deaerator level is 65%
• Ø  Ensure Feed water tank level is 70-80%
• Ø  Ensure DM water storage tank levels are 80-90%
• Ø  Ensure cooling tower level is 80%
• Ø  Ensure tank levels showing in are matching with local gauge glass levels.
• Ø  Ensure feed water parameters are normal

 

Fuel

• Ø  Ensure abundant Bagasse/coal is available at yard
• Ø  Ensure Bagasse/coal parameters (Moisture, Ash & GCV) are normal
• Ø  Ensure bagasse silos are full and silo gates are open
• Ø  Ensure coal bunker level is 80-90%
• Ø  Ensure tractor dozers and JCBs are available at yard
• Ø  Ensure Diesel level at DG tank is 90-95% and another 3000-4000 litres diesel is available for immediate top up
• Ø  Ensure Diesel transfer pump is healthy and running normal

 

11.Boiler start up Procedure

• Ø  Stack fire wood/ baled bagasse inside the furnace for light up
• Ø  Start ACWP pump and ensure all the parameters like discharge water pressure, bearing vibrations, temperature etc are normal
• Ø  Start the Instrumentation air compressor and ensure all the operating parameters are normal by evidencing loading and unloading pressures are as per desired.
• Ø  Start service air compressor and ensure all the operating parameters are normal
• Ø  Start the ESP rapping system
• Ø  Start the ash handling system
• Ø  Start the coal spreaders
• Ø  Start the Sub merged belt conveyor (SMBC) and ensure enough water level in conveyor trough.
• Ø  Fire the fire woods and slowly rise the furnace temperature up to 175-200 deg C
• Ø  Start Bagsse handling system and maintain silo levels 100%
• Ø  Start ID fan at 10% reference followed by FD & SA fans and ensure balanced draft in furnace i.e + or – 2 to 3 mmwc and ensure fans operating parameters (Bearing vibration & temperature) are normal.Note that, initially one stream of fans shall be started and second stream shall be started once boiler reached at rated main steam pressure and temperature.
• Ø  Ensure SA fans static pressure at discharge is 400-450 mmwc initially and increase gradually based on fuel feeding.
• Ø  Start CR fan and maintain discharge static pressure 350-400 mmwc
• Ø  Start fuel feeding system, start bagasse screw feeder followed by bagasse extractor at 5 to 10% reference initially
• Ø  Gradually go on increasing the furnace temperature by increasing fuel feeding slowly.
• Ø  Based on fuel feeding, gradually rise ID, FD & SA fans speed and always ensure balanced draft in furnace.
• Ø  Keep continuous communication with Boiler field team and get the feedback on combustion in furnace.
• Ø  At drum pressure 2 kg/cm2 close drum air vent valves
• Ø  At steam pressure 3 to 5 kg/cm2, close all the super heater air vent valves.
• Ø  Start HP & LP dosing system and ensure operating parameters (Discharge pressure, flow & tank levels) are normal.
• Ø  Start rising the Boiler pressure and temperature as per OEM given start up curve.
• Ø  Keep crack open CBD valve
• Ø  If drum level is coming down, start the BFP and maintain the drum level. Initially maintain the drum level through single element (30%) control valve and keep it in manual mode.
• Ø  If drum level increases, give blow down through IBD. Note that, during start up drum level can be maintained in the range of 30 to 80%. Do not allow to cross drum level > 85%
• Ø  At 5 to 7 Kg/cm2 main steam pressure, close the primary super header drain valves.
• Ø  At pressure 7 to 10 kg/cm2, stop the firing & give blow down through IBD and water wall bottom headers for 1 mi. Ensure normal drum level (40-50%) during blow downs.
• Ø  At 7 to 10 Kg/cm2 main steam pressure, close the secondary super header drain valves.
• Ø  At 10 to 15 Kg/cm2 main steam pressure, open start up vent control valve 10% and then close the radiant super heater header drain valves.
• Ø  Gradually open the start-up vent control valve as per requirement to ensure minimum cooling steam flow through super heater coils and also to rise the main steam temperature
• Ø  Always ensure that, minimum cooling steam is flowing through the super heaters when Boiler is under firing.
• Ø  Keep on noting down the Boiler all headers thermal expansion readings at various temperature and pressure. And escalate if thermal expansions found non-uniform.
• Ø  Ensure Ash is discharging from all the hoppers (Plenum, Economiser, APH and ESP hoppers)
• Ø  Ensure bearing vibrations of BFP and fans are normal.
• Ø  Ensure fuel feeding and handling system are running normal.
• Ø  At 40-45 kg/cm2, gradually open the main steam by pass valve and start to charge the main steam line.
• Ø  Check and confirm the steam and water coming out from main steam drain lines.
• Ø  Gradually increase the main steam pressure and temperature and open main steam stop valve slowly (MSSV) after ensuring steam line has heated up and condensate has been removed completely. Note that, before opening MSSV, pressure at inlet and outlet of the valve is almost equal, this helps for easy operation of the valve
• Ø  After opening MSSV, close by pass valve.
• Ø  After ensuring proper charging of the main steam line, give clearance to Turbine engineer for vacuum pull up and other start up activities. And open the MSSV as per their requirement.
• Ø  Increase the main steam pressure and temperature up to rated parameters i.e pressure 110 kg/cm2 and Temperature 545 deg C
• Ø  At rated pressure and temperature, start the second stream of fans i.e ID, FD & SA fans & ensure fan & motor’s bearing vibration and temperatures are normal.
• Ø  When boiler steam flow reaches more than 30% of its MCR, close the start-up vent control valve.
• Ø  Charge ESP at inlet flue gas > 120 deg C
• Ø  After normalisation of start-up, once again ensure all equipment bearing vibration and temperatures are normal and there not exist any abnormality.
• Ø  Take drum level controller in Auto mode.

Read more>>>Formula for Boiler calculations